The version of Sterecon for SGI workstations has been completed, and is in routine use, although occassional debugging still takes place. An SGI workstation has been purchased from this grant to replace the earlier Sun-based system, although the old system is still in use, and will be kept until the hardware fails. A full description of the current version of Sterecon was published in J. Structural. Biol. (1995), in which the system is offered for distribution. So far the labs of three collaborators, R.G. Summers of SUNY Buffalo, S.L. Erlandsen of U. MN., and R.A. Horowitz of U. Mass, are recieving the system. Extensive use of Sterecon has been made for segmentation of electron tomographic volumes, and the interface to SGI Explorer and SceneViewer for surface rendering has been very useful for making animations and striking illustrations. Development has begun on a completely new version of Sterecon. The new version is being written in C++ instead of Fortran, will have a more modern user interface, and makes use of Open Inventor. The development of the new version is a long-term project.